1. Field of the Invention
The present invention relates to an electronic paper display device and a manufacturing method of the same, and more particularly, to an electronic paper display device having a microcapsule disposed in a cell defined by a barrier layer and maintaining a ratio of minor axis to major axis of 0.9 to 1, and a manufacturing method of the same.
2. Description of the Related Art
A liquid crystal display (LCD), a plasma display panel (PDP), an organic electro-luminescence (EL) device, and an electronic paper display device have been widely propagated as next generation display devices.
Among them, the electronic paper display device can be flexibly bent, and a production cost thereof is much lower than those of other display devices. Further, since the electronic paper display device does not require background lighting or continuous recharging and can be driven with very low energy, it has very high energy efficiency. Further, since the electronic paper display device is clear, has a wide viewing angle, and has a memory function to maintain displayed characters or images even at the time of instantaneous power cut-off, it is expected that the electronic paper display device will be widely used in a broad field such as foldable screens and electronic wallpapers as well as print media like books and newspapers.
Meanwhile, technical methods, such as an organic EL method, a reflective film reflection type display method, an electrophoresis method, a twist ball method, an electrochromic method, and a mechanical reflection type display method, have been independently developed to implement the electronic paper display device.
Among them, the electronic paper display device using the electrophoresis method includes a first electrode, a second electrode, and microcapsules which are interposed between the first and second electrodes and each of which has a core including electrophoretic particles and a shell surrounding the core. At this time, the microcapsules may be fixed by a binder layer provided between the first and second electrodes.
However, the binder layer may cause voltage drop and parasitic capacitance of the electronic paper display device or greatly affect electrophoretic property of the electrophoretic particles.
Furthermore, since the microcapsules may not be uniformly disposed in the binder layer, and so there may be some regions in which the microcapsules are overlapped with each other or not disposed, there was a problem of deterioration of a contrast ratio of the electronic paper display device.
Conventionally, in order to improve the contrast ratio of the electronic paper display device, the microcapsules have been formed to be flexible and easily deformed. This is because the conventional microcapsules are easily dispersed by self-weight after being filled between the first and second electrodes, finally the microcapsules interposed between the first and second electrodes come into contact with each other, and density between the microcapsules filled between the first and second electrodes can be improved.
However, since the microcapsules can be easily deformed due to flexibility, it was not easy to handle the microcapsules. Further, it was difficult to uniformly dispose the microcapsules between the first and second electrodes due to cohesion between the microcapsules.